1. Field of the Invention
The invention relates to a film capacitor including stacked dielectric films on each of which electrode metal is evaporated.
2. Description of Related Art
Generally, there is known, for example, a metallized film capacitor that is used to smooth an inverter circuit for an automobile (see Japanese Patent Application Publication No. 2006-269727 (JP 2006-269727 A)). The metallized film capacitor described in JP 2006-269727 A includes a first metallized film and a second metallized film. The first metallized film includes an evaporated metal electrode. The second metallized film includes an evaporated metal electrode, and the evaporated metal electrode is split by slits into split electrodes.
The split electrodes of the second metallized film are connected in parallel with each other by fuses. The surface roughness of the evaporated metal electrode side of the dielectric film that constitutes the second metallized film is smaller than the surface roughness of the evaporated metal electrode side of the dielectric film that constitutes the first metallized film. According to JP 2006-269727 A, protective performance improves due to the side having a high surface roughness, and dielectric strength (withstand voltage) and service life improve due to the side having a high surface roughness.
There is known a metallized film capacitor in which adjacent evaporated electrodes are opposed via a dielectric film, each evaporated electrode is split into a plurality of small electrodes to form fuse portions, one of the dielectric films, which overlaps with the evaporated electrode of the other dielectric film, has holes or recesses in regions that overlap with the fuse portions of the other dielectric film (see Japanese Patent Application Publication No. 2007-67169 (JP 2007-67169 A)). According to JP 2007-67169 A, pressing action, in which the one dielectric film presses the fuse portions and their vicinities of the other dielectric film, is reduced, and therefore, it is possible to provide a metallized film capacitor having high protective performance and high safety.
In the above-described film capacitors, a further reduction in size is required. In addition, a dielectric film is becoming thinner. In the metallized film capacitor described in JP 2006-269727 A, if each dielectric film becomes thinner, it becomes impossible to sufficiently roughen the evaporated metal electrode side of the dielectric film that constitutes the second metallized film, that is, it becomes impossible to provide small unevenness, with the result that it becomes difficult to ensure protective performance. In the metallized film capacitor described in JP 2007-67169 A, it is difficult to align the holes or recesses of the one dielectric film with the fuse portions of the other dielectric film.